Automatic telephone system



R. F. STEHLIK AUTOMATIC TELEPHONE SYSTEM July 17, 1928. 1,677,413

A I] Filed May23, 192'! 4Sheets-Sheet 1 1mm? 7 wm 512mm July E7, 1928 AUTOMATIC TELEPHONE SYSTEM STEHLIK v led May 23, 1927 Inuefi or" Fgilph I? SEE fig i July 17', 1928. 1,677,413

' R. F. STEHLIK AUTOMATIC TELEPHONE SYST EM Filed May 25, 192"! 4 Sheets-Sheet 4 Rudalph F hlik Patented July 17, 1928.

nan srras fares r arise] VRUDOLIH F. STEHLIK, OF CHICAGO, ILLINOIS,- ASSIONOR TO 'RESERVE HOLDING- COMPANY, OF KANSAS CITY, MISSOURI, A CORPORATION OF DELAWARE.

AUTOMATIC TELEPHONE SYSTEM.

Application filed. May 23,

This invention relates in general to automatic telephone systems, but is more particularly concerned with such systems in which line finders are employed to connect. an idle selector switch with a calling line, and the principal object of the invention, briefly stated, is the production of a new and-im: proved finder switch system, the improvements tending to make the system more reliable in its operation as well as cheaper to install and maintain.

Heretofore finder switch systems have been devised along two general plans, the

one employing a common control mechanism which directively sets the wipers of the finder switch upon the contacts of a calling line. The other employed finders of the so called selective type, that is the finder switch is moved either under its own control or under the control of a common equipment, and as it moves it individually tests each contact over which its wipers pass, in search of particularly marked contacts designating a calling line. If the finder switchesare of a two motion Strowger switch type, whose wipers are moved first. in a vertical direction to find the level containing the contacts of the calling line, and then in a horizontal direction to engage the particular contact set of the calling line, both these finder systems have their advantages and their disadvantages; In adaptations of this kind, the directive principal of operation is particularly advantageous in moving the wipers of the finder switch in the first or vertical direction, and the selective plan of operation is particularly advantageous in moving the tancously.

927. serialire-193,432.

steps to contacts the selected level to select; one of the oh'e hundred lines in the basic groups served by the switch; Finder switch practice employed heretoforev has brought out'certain advantages in increasing thenumber ofli'nes over'fwhose contacts one finder sw tch sweeps,,that isby increasing the line capacity of the finder from onebasic hundred lines group to two hundred basic groups, certain advantagesuntrunkmg' and certain economies in equipment are realized By equipping the Strowger switch with two sets of wipers, Iain able to double the capacityof the finder, arranging it so that after the wipers have been elevated to 'a desired level, tests are made on the two'sets of con tacts in'that level, thatis lines of the second hundred'linebasic groups are tested simul Accordingly as a further object of my in vention l' provide a finderswitch system of the twohundred line capacity, in which systemxl provide, simultaneous hunting in a level of each of the two hundred line groups served byv the finder.

To be eminently successful a finder switch system must operate quickly, to reduce the length of time elapsing between the removal of the receiver by a calling subscriber and the reception'of dial-tone by him, to indicate that the vswitch mechanisms are in proper position to receive the directive digits of his call. H a finder switch moves in a vertical direction firstand then. in a rotary direction,

a considerable amount of time is requiredto reach the contacts of a line whose finder bank designation is of a highorden'that is lines in the 60, 70, 80, 90 'and 0 groups. v If,

line ,95 for example is the calling line, the

finder switch ofthe systems devisedheretofore would be required to take ten vertical steps, followed by five steps in a horizontal direction. eration would be relatively long.- However if line 25 happens to be the calling li ne,'the finder switch is required to take onlytwo steps in a vertical direction followed .by five steps in ahorizontal direction and the time. required for this operation is, relatively short- From the foregoing it will be ap parent that the calls to all of the-lines in the The time required for such 0p first five tens groups of the switch can be made in a sufiiciently short interval of time,

while the calls from all of the lines in the upper five tens grou s of the bank, that is groups 6 to 10 inc usive,require arelatively longperiod of time. To remedy this condition, I employ a system of preferential service, in which the lines in the first five tens groups of each of the one hundred line basic groups handled by the finder are grouped together and handled by one group of finders, thru a control equipment come i mon to that finder group. The lines of the second five tens groups of both of the hundred line basic groups are grouped together and handled by a second group of finder switches, in which latter finder switches, tens groups #6 appears as level #1, tens group #7 as level #2, and tensgroup #10 as level #5. By this arrangement I have provided, a finderswitch system in which no finder switch is required to take more than five vertical steps in the normal course of events to reach the level containing the contacts of a calling line. However, in order to provide for emergency service, each finder switch ofthe group has access to the entire two hundred lines, the tens groups contain ing these lines occurring in regular consecutive order in the banks of the first finder switch group, and in reverse order ,in the banks of the second finder switch groups, that is tens groups 6 to 10 appear as 1 to 5 inclusive in said second group, tens group 1 a pears as level 6, 2 as 7,. 3 as 8, and 5 as 10.

y this arrangement each finder switch has access to the entireitwo. hundred line group,

i but serves only the one hundred lines appeering inthe particular group of levels to which it has first choice in thenormal workin of thes stem, andserving lines in the ot er group y taking more than'five vertical steps when thetrafiic inthe group is heavy or when an emergency arises. f By this system of preferential service .which I employ as a further object of my invention, I am able to materially speed up service by reduring the average time required to elapse before the calling subscriber hears the dial which are assumed to be corresponding lines in each of the one hundred line groups served by the finder switch. That is line B is assumed to be line number 115 and line A 215, in which case the contacts of the two lines will be simultaneously engaged by the switch wipers. In Fig. 1 I also show the finder switch F which is a two motion switch of the Strowger type, whose wipers are moved first in a vertical direction to select the level contained in the contacts of the calling line, and then in a rotary which the finder switches of the group con- '7 taining the finder F are. selected and con-- trolled. -The finder allotter FAl is mechana ically like the well known'rotary lineswitch,

whose wipers have no normal position and move in one direction. only, the mechanism being arranged to move the wipers when the magnet of the switch deenergizes.

In Fig. 2 I show the level relay group comprising relays 201 to 205, which relays are controlled by the start wire leading from the lines of the respective tens groups, to mark the designation of a calling line in the banks ofpthe vertical sending switch. In Fig. 2 I also show the sending switches S1 and S2, S1 beingassociated with the control equipment E1 of Fig; 3 to assist that equipment in controlling the finder switches of the #1 group. I Vertical counting switch S2 is associated with the control. equipment (3E2, of F ig. 4 to assist that equipment in controlling the .switches of the second finder group. 0 In Fig. 2 I also show the lever relays 206 to 210, which are controlled over the start wires leading from the sixth to the tenth tens groups of lines being energized over those start wires, so mark the designation of a calling one of theselines in the banks of the sending switch YS2. It will be noted in Fig 3 that when the relay 201 is energized responsive to a call started by a lincin the first tens gro'.ip,.that is the line 215 for example. that line is marked calling:

in the .banks of VSl and V52. being marked as the first contact over which the wiper 221 of VSl rotates and being marked as. the sixth contact over which'wiper 225. of V82 rotates. energization of relay 206 responsive to the initiation of a call by a line in the sixth tens group of lines, will be marked as the first contact in the banks over which wiper 224 of the vertical sending switch VS2'n1oves, and willalso be marked as the sixth contact in the bank over which wiper 220 of the counting switch .YSl rotates. By this arrangement it will be seen that the first .fi ve Similarly it will be noted that the tens groups are first choice levels to the switch VSl, and the second five tens group,

that is groups 6 to 10 inclusive, are first choice to the switch VS2. The purpose of this will be more fully brought out hereinafter.

In Fig. 4, I show finder allotterFA2 and the control equipment CB2, which is a duplicate of the equipment shown in Fig. 3. The equipment (IE2 controls finders of the group 2 which are preselected by the finder ail-- lotter F A2. The finders of group 2, being duplicates of the finder F, are not shown in the drawing. Group 2 finders have access as first choice to tens groups 6 to 10, and as second choice to tens groups 1 to 5, and are normally operated in response to a call in anyone of the tens groups 6 to 10.

Throughout the drawingsI have shown a plurality of batteries, to avoid an unnecessary complication of the figures. ln airinstallation of the system of my invention, there would be but one battery, preferably with its positive pole grounded.

Assume now that the line A initiates the call, line relay 2 is energized over the loop circuit, sending a ground over the start wire 64 to energize the level relay 201, to mark the first .level calling in the banks of VSl. Energization of level relay 201 places a ground on the group 1 start conductor 27?, starting the control equipment 0E1 into operation. viously preselected the finder F, that finder is now started by the control equipment (IE1 and takes one vertical step, at which time the vertical sending switch VSl encounters the marked contact to bring .the finder to rest. ranged to operate upon revertive pulse from the finder F, that is CE closes an impulsing'circuit to the magnet of the finder that circuit being branched oil to include the magnet of the counting switch CS1. \Vhen the finder magnet has fully. energized, it closes a circuit to send back a pulse to energize a pulse terminating relay, which upon energizing opens the circuit both to the finder magnet and to the counting switch magnet. When the pulse terminating relay is energized, circuit is completed from the marked contact encountered by thefswitch CS1, to the change over relay, which energizes and locks' The energization of the Finder allotter FAl having pre- The control equipment CEl is ar F encounters batterypot-ential, which potential marks the line as calling, at which time, switch through relay 802 of the control equipment CEI is energized, pulsing ends, switching relay of the finder F is energized, and thecalling line is seized by the finder F and made busy.

Control equipment 0E1 is released by the.

energization of the switch through relay, and returns to normal under its own control.

During the interval required for CEl-to re-' turn to normal, start conductor 27? is ex tended into control equipment (3102 that in case a call is waiting in the group 1, that is a call from one of the first five tens levels, that call can. be immediately handled by group 2 provided that the latter equipment; is idle at the moment. Counting switch CS1 moves to its normal position under control of a local circuit, stopping when the home position is reached. When the control equipment gets to normal, finder allotter F A1 is started to searchi'or the next idle finder of the group, which is preselected and connected with the control-equipment CEl preparatory to handling the next call.

Similarly a call initiated in a line of the second group, that is in tens groups 6 to 10', energizes the corresponding levelrelay over start conductors, not shown, to ground group 2 start conductor 371, to start control equipment 0E2 in operation. The idle finder, not: shown, which finder allotter FA2 has pre selected, is started, being operated in a man-- ner identical with that pointed out in con-' nection with finderF. Group 2 finders controlled by equipment SE2 and counting switch VS2 have normal access to tens groups 6 to 10, those levels appearing as levels 1 to 5 respectively in the banks of the finders. The finder takes the required num ber of vertical steps, whereupon switchover relay 406 isenergized and the finder caused to move in, a rotary direction underthe control of its private wiper. When the calling line has been. reached, the control equipment is released, the finder is switched through, and the start conductor 371 is extended back through springs Q36 and 4-25 to the relay309' of the control equipment 0E1, so that in" case another call is waiting in group 2, that call can be instantly handled by group '1 provided there are no group 1 calls at the instant.

Returning now to the operation of finder F, it will be noted that there are two switching relays 5 and 6, and that ground on conductor 71 is projected to the lower terminals of both of the upper windings of these relays. The other terminals of these windings are terminated on wipers 54 and 51 respectively, those two wipers engaging the private contacts in the selected level. Should either of these private contacts-be at battery poten-' tial, corresponding finder switching relav waiting will be energized, the switch through relay of the control equipment CEl will be energized, and the finder will stop upon the contactset. In other words, wipers 51 and 54 simultaneously hunt in the two groups of lines. If for example lines A and B "would initiate a call simultaneously, or line A should initiate a call slightly ahead of line B, finder equipment CEl would be started by a call initiated by line A. \Vhen the wipers 51 and 5t encounter the contacts associated with lines A and B, circuits should be completed for both relays 5 and 6, one or the other of'these relays would pull up first. No special adjustment is required to cause this action, as it is impossible to construct two relays exactly alike in time constant, as would be necessary if both relays 5 and 6 wereto completely energize simultaneously. Assume the line 5 pulled up first, line A would'get the call, line B would maintain a ground on the start wire 64, start relay 201 would be energized, and when the control equipment @131 switched through, the call pending on line B would be handled by control equipment E2, if idle.

When the control equipment (1E1 is started responsive to a ground upon a start conductor 277, the selector S is seizedby ground on conductor 67 projected from the control equipment 0E1. Line relay 7 of selector S is energized, and closes the well known circuit for the release relay 8, which energizes and at spring 47 extends ground back on release conductor 68. Therefore when switching relay or 6 of the finder is energized, it locks to the release trunk conductor through its lower winding independent of its energizing circuit, and is maintained in energized position as long as the release trunk conductor is grounded;

In case the finder switch F happens to be the last idle finder in the group, when it is seized and the selector associated with it energized, ground is removed from the busy is energized, and the start conductor 277 eX- tended to the control equipment 0E2, to enable that equipment to handle calls originating in group 1.

Having thus described my invention in general I will now proceed with a detailed description of its operation.

Line A calling.

Assume now that line A initiates the call,

by removing the receiver from the switch hook.

A circuit for line relay 2 is then closed from ground through springs 22, line station A to the line conductor 61, springs 20, through the winding of line relay 2 to battery; Line relay 2 energizes over this circuit and at springs '23 prepares a point in the circuit of cut-off relay 1, by connecting the upper windingvof that relay through the conductor 76 to the private contact 7 6 in the finder switch bank. Thus the energization of'line relay 2 places battery potential upon the contact 7 6, to make the line calling. Energization of line relay 2 at springs 24 closes a circuit for the level marking relay 201 traceable over conductor Get through the winding of relay 201 to battery. Relay 201 energizes over this circuit, and at springs 230 places a ground on the group 1 start conductor 277. At springs 231, relay 201 disconnects conductor, 261 from conductor 260 and connects it to conductor 265, for a purpose which will be apparent hereinafter. Starting equipment 0E1.

Ground placed upon start conductor'277 by relay 201 traverses a circuit'from that conductor through springs 3 19 and its break cont-art, spring 355 and its breakcontact, conductor 374, springs 126, conductor 376, through the Winding of start relay 308 to battery. Start relay 308 energizes over this circuit, preparing the equipment CEl to handle the call from the #1 group line Ar Energizatien of relay 308 closes a circuit irom grounded conductor 377 through spring 353 through springs 351 through the Wind ing of slow acting relay 301 to battery, energizing that relay which at springs 326locks itself and relay 308 in energized position over a circuit traceable from ground through springs 326, conductor 391, thence through springs 351 conductor 392, the winding of relay 301 to battery, and through springs 353, and the winding of relay 308 to battery. The energization of relay 301 at springs 324' opens a point in the circuit of the motor magnet 310 of the finder allotter FAl, to

prevent that magnet from energizing at this 7 time. At springs 325, relay 301 closes a cir-' cuit for the upper winding of line relay '7 of the selector S, traceable from ground through springs 325, wiper 321, now associated with contacts terminating conductor 67, through that conductor, through the upper winding of relay 7 to battery, relay 7 energizing over this circuit to close the obvious circuit for relay 8, whch energizes and at springs 47 places a ground uponthe release trunk conductor 68, to mark the selector busy and for other purposes which will be hereinafter explained. Relay 301 at springs 327 and its break contact opens a point in the circuit of the upper windng of all finders busy relay 306 to prevent that relay energizing at this time.

Vertical impale mg, Energization of relay 301, at spring 327 and its make contact closes a circuit for the vertical magnet 9 of the finder F, traceable V the bank over which wiper 225 sweeps conductor 378, springs 357, conductor 394, springs 336, Springs 331, wiper 322- the control equipment CEl also closes a circuit through winding of magnet 305, over a circuit traceable from ground on springs 327, normally closed contacts controlled by armature 330, springs 334, through the winding of the magnet 305 to battery. Relay 305, being slow to pull up, does not attract its armature immediately. The energization of the vertical magnet 9, in addi- A tion to advancing thewipers one'vertical 5 step, closes the revertive pulse circuit traceable from ground through springs 36, conductor 77, through the upper wind- 'ing of relay 303 to battery, energizing the relay 303 which at springs'333 opens the circuit ust traced tor magnet 211 of the counting switch VSl, and at springs 331 opens the circuit just traced for the vertical magnet 9, andat springs 334 opens the circuitfor theslow to pull up relay 305. The deenergization of magnet 211 advances wipers 220 to 223 inclusive one step, the deenergiza tion of vertical magnet 9 opens a circuit for relay 303 at springs 36. Inasmuch as the instant call is ifrom a line terminating in the first level of the bank of the finder of F, only one vertical impulse is required, and switch over to rotary occurs at this time. However it more than one vertical impulse is required, the foregoing circuits would again be completed, the verticalmagnet being energized through wiper 221 now in engagement with its second bank contact, conductor 261, through the spring 231 and its break contact, of the first level vertical marking relay 201, to conductor 260, and thence over the previously traced 'circuit to the magnet. Thisimpulsing would continue until wiper 221 encountered the contact whose circu t to conductor 260 was broken by the lowermost springs of one of the vertical marking relays 201 to 205 inclusive, at which 'time'the change over torotary would occur:

Change ooerto 20mm; impaled/Lg.

Returning now to the call in progress, when the magnet 211 has advance its wipers into engagement with their second set or" contacts, wiper 211 encounters conductor 261, which is connected to conductor 265 by springs 231 of energizedfirst level relay 201. A ground now placed on conductor 272, as previously explained, extends over a circuit through wiper 221, conductor 261, springs 231, conductor 265, conductor 380, springs 358, conductor 395,-,springs 338, through the upper winding of relay 304, the upperwinding of relay 303 to battery. Relays 304 and 303 energize over this circuitfthe former locking itselfthrough'its lower. winding and springs 337 through ground through spring 327 and its make contact. break contact opens a point in the circuit of the motor magnet 211 of the vertical counting switch S1, to prevent further energization of that magnet at this time, and at spring-339 and its make contact extends the circuit to the rotary magnet 10 of the finder F, to energize that magnet to position the wipers of the finder F upon the calling contacts in the selected level; At springs 338,

relay 304 opens the initial energizing oircuit for itself and relay 303,permitting relay 303 to fall back. Relay 304, spring 336 opens a point in the circuit of the-vertical magnet 9 of the finder F, to'prevent further energization of that magnet at; this time.

The energization'o't' relay 304, at springs 340 closes a restoring circuit for the vertical counting switch CS1, traceable from ground through springs 340, conductor 275, multiple contacts of the bank over which wiper 223 sweep, wiper 223, spring 248 and itsbreak contact through the winding of the magnet 211 to battery. The magnet 211 energizes over this circuit and at springs 248 opens its own circuit, whereupon the" armature fallsbackand advances the wipers 220 to 223, inclusive, onestep and the springs 248- reclose the circuit of the magnet. Magnet 211 therefore operates in a buzzer like fashion advancing the wipers until wiper 223 engages its normal position contact, which is not connected to the multiple with the remainder of the contacts.

circuit through which the'rot'ary impulsingf of the finder F will be subsequently controlled ,at spring 333 opens a point in the energizing circuit of the magnet 21.1 of the vertical counting switch CS1, the samepoint being subsequently included in the circuit of the rotary magnet 10 of the finder F, to

Relay 303' upon energiz ngat springs 331 opens a Relay 304, at spring 339 and its I prevent that magnet from energizing prior to the restoration of the relay 303. At the springs 334, relay 303 o ens the circuit of relay305, and permits t at relay to'restore as before.

Rotary impala-tag.

7 Relay 303 restores immediately upon the opening of the circuit through springs338, closin the circuit to the rotary magnet tracea ,lefrom ground through spring 327 and its make contact, normally closes springs controlled by armature 330, springs 333, spring 339 and its make contact, wiper 323 now engaging conductor 73, through the winding of rotary magnet 10 to battery, energizing that magnet which advances the wlpers 50 to 55 inclusive of the finder F on Qthe first bank contact of the first level.

Magnet 10 upon energizing closes at spring 7 37 a circuitlfor the pulse terminating relay 303, which energizes and at springs 33v opens apoint in the circuit of the magnet 10, permitting that magnet to fall back in readiness for another pulse. The circuit to slow to pull up relay 305 is closed through springs 334, when relay 303 deenergizes, as before, but .in thenormal working of the systems the rotary magnet 10 energizes before the relay 305 has. had time to pull up, so the closmgof that circuit is without particular efiect at this time. -When the wipers 50 to 55 inclusive areadvanced into engagement withthe first bank contact, wipers 51 and 54- engage the private contacts associated with the first line in" the first level, however sincethat line is assumed to be in an uncalling P sition at this time, no potential will be present upon the private contacts vandno circuits will be completed through the wipers. Impulsing therefore continues when relay 303 restores, the cycle of. operation continuing through five impulses at which time wipers 't0 inclusive are in engagement with thefifth contactset in the first level, the contact set containing the,

terminals of; the line A, which is at this time assumed to he the callingline.

-Swit07uTng through the finder and control I eqmpment. Each time the impulse relay 303 is energized, the testing circuit is projected from grounded spring 327 through the normally closed contacts controlledby armature 330,

and ,54 encounter the contacts of a calling relays and relays 302 and 303 of the control equipment, energizing those relays to switch through the finder and control equipment. Since line A is calling, and wiper 54 is now assumed to be in connection with contact 76 associated therewith, the circuit for relay 5 will be completed through wiper 54 and that contact, conductor 76, springs 23, upper winding of cut off relay 1 to battery. Cut off relay 1, switch through relay. 5, switch through relay 302, pulse terminating relay 303 are all energized ormaintained energized over this circuit. Relay 5 upon energizing locks itself through its lower winding and contact 34 to the grounded release trunk conductor 6.8, that conductor beinggrounded by the release relay 30f the selector switch S as has been hcreinbeforc explained. Relay 5 at springs 45 connects the negative trunk conductor 67 through the wiper 53 to the negative line 61, and at springs 43 connects the positive trunk conductor 69 through wiper 55 to positive line 60. At springs 33 and 34,; relay 5 connects a release-trunk conductor 68 to the Wiper 54, contact 76, conductor 76 through the upper winding of relay 1 to battery, locking that relay in its energized position nde- H pendent of the ground on springs 327 through which it was initially energized.

The energization of relay lat springs 20 i tone is audible to-the calling subscriber, be-

ing applied through the ground side of the relay 7,;by the dial tone generator, not

shown, to apprise the calling subscriber at A of the fact that the switches are now in readinessto receive the directive digits which he produces with his calling device.

Returning now to the control equipment 0E1, the energization of switch through relay 302 as hereinbefore explained, closes that spring, 328 a circuit for the magnet 310 of the finder allotter FAl, that circuit ineluding conductor 390, springs 346, springs 348 and the magnet winding energizing that magnet to .advancingthe wipers 320 etc., of the finder allotter onto the next contact. Energization of relay 302 at springs 329 closes a locking circuit for itself, through those springs and springs 327 to ground, and at springs 330 relay 302 opens a point in the impulsing circuit, to preventfurther operation of the motor magnets at loo 7 All this time. Ground projected onto conductor 390 by springs 328, traverses the upper winding of the relay 307 to battery, energizing that relay which atsprings 351 opens the locking circuit of relay 301, permitting that relay to deenergize. Relay 301 being slow to release, remains in its energized position for a definite interval after the circuit through its coil has been opened. Relay 307 upon energizing at springs 363 closes a circuit from the lower winding of relay 307.to conductor 276 through multipled'contacts over which wiper 222 of the vertical stepping switch VSl .rotates. In the event that the vertical switch VSl has not as yet arrived at its normal or home position, relay 307 will be locked in energized position, pending the return to normal of the switch VSl. in a call of the character justdescribed, VSl will bein its normal position prior to the energization of relay 307, and it is only in the case of an emergency that this lockingthat magnet 211 of the switch VSl will receive a supply of ground if it is not as yet in its normal-position.

' Relay- 301 whose circuit wasopened as explained before, restores after an interval, at springs 326 opens the circuit of relay 308, permitting that relay to restore to normal. At springs 327, relay 301 opens the locking circuit of relay 302, and the locking circuit of the switch over relay 304, permitting "those relays to restore to normal to prepare the control equipment for handling another call. The restoration of relay 301, at springs 324 closes a circuit from the test wiper 347 oi the finder allotter F111 to the magnet through the interrupter springs348,

preparing that magnet for automatic selecti'on of the next idle finder of the group.

If the next finder switch, upon whose contacts the wipers of the finder allotter are now standing happens to be busy, ground from release trunk conductor 68 will be projected through off normal springs 45 and its break contact to conductor 75, or if the finder switch is in its normal position, ground will be put on conductor 75 by the off normal spring and its make contact, and in either event wiper 347 will encounter ground to complete the circuit through springs 345, springs 324, conductor 388. springs 348,

winding otmagnct 310 to battery, energizing In the normal operation of systems.

' relay 307 to battery.

back and advance the wipers of the finder allotter F141 one step onto the next trunk. Magnet 310 upon falling back,.closes its circuit at 348, and if wiper 347 is then standing on a grounded contact, magnet 310 will be again energized to advance the wipers another step. This'magnet therefore operates in a buzzer-like 'filSlllOIl as long as the Wiper 347 encounters grounded contact, coming to rest upon the first ungrounded contact which is associated with the first idle finder of the group. When the finder allotter F111 finds thencxt idle finder of the group, control equipment C191 is in readiness to handle the next call which may be placed upon it.- During the interval of wiper 347 is engaging grounded contacts, relay 307 is maintained energized from the grounds pulsed up by wiper 347, over a circuit extending tliu'ough spring 345, spring 324, spring 346 and its break contact through the upper winding of Thus relay 307 is energized to open, at springs 350, the circuit of relay 309, and at springs 349, the circuit of relay 303, to prevent the starting of a call in the eontrolequipment 0E1 prior to the time that the finder allotter has preselected an idle finder.

A oaZZ in. the second group.

Assume now that a line in the second group initiates the call, and assume furtherthat line 18 in the seventh tens group.

p The line relay ofthat line will place ground on the seventh start COIIClUCtOI,'I1O1 shown, to energize levcl relay 207. Relay 207 upon energizing at springs 242 grounds the group 2 start conductor 271, the circuit extending "through spring 436 and its break contact,

425 and its break contact, conductor 372,

springs 354, conductor 373, through the winding of start relays 402 to battery, encrgizing that relay to prepare the control equipment C132 to handle the call. Start relay 402 looks itself through springs 429 to the grounded springs 47 0', start wire ground being first projected through springs 429 to energize the auxiliary start relay409 over thecircuit including springs 438. The energization of relays 402 and 409 prepare control equipment 0E2 to handle the call, that equipment having control of a finder of the second group through the finder allotter F112. Since the'findcrs of the second group are duplicates to those shown in Fig. 1, at F,

Returning now to the energization of relay 207, springs 241 break the connection between conductors 270 and 269, thereby pre-' paring circuits through which the vertical counting switch CS2 willv terminate the verti-- cal impulsingea'fter two impulses have been sent. It will be remembered that the seventh tens group lines appear in the second level of the finders of group 2, therefore in order to reach these lines those finders must take two vertical steps.

Vertical pulsing. v

' 381', wiper 224 of counting switch CS2,.con

ductor 271 which is engaged by that wiper, conductor 377, springs 433, conductor 474, springs 456, wiper 422 of the finder allotter and thence through the vertical magnet of the finder switch. A' parallel path extends fromthenormally closed springs controlled by armature 468, through springs 465 to the auxiliary impulse relay 405 to battery and another. parallel path through spring 464, spring 459 and its break contact, conductor 385, through the winding of the stepping magnet 212 of the counting switch CS2, to battery; The vertical magnet of the finder and the. magnet 212 of the counting switch CS2, are energized over these circuits, and the auxiliary impulse relay 405, being slow to pull up is not energized in the normal working of the system. hen the vertical magnet of the finder has been fully operated, a. revertive pulse is returned over pulse conductor 476, closing its circuit through the I" upper winding of impulse relay 407 to impulsing, circuits just traced.

battery, energizing that relay, which at springs 464, 465' and 462 open the various 7 Counting switch CS2, and the finder take one step,

. magnet of the finder falling back to remove the ground from the conductor 476 to permit the impulse relay 407 to restore, whereupon the iinpulsing circuit is again closed and the finder and the counting switch VS2 take another step.

Last vertical impulse.

Since the calling line is assumed to be in the seventh tens group, which appears'as the second level in the second group of finders,

two vertical impulses are all that are required, and when the counting switch VS2 counting switch CS2, that wiper now being in engagement with its third bank contact through which conductor 269 is connected,

to-spring 241 its make contact, conductor 379, springs 434, springs 458, through the upper winding of switch over relay through the upper winding of impulse relay 407 to battery. Switch over relay 406 and impulse relay 407 are energized over this circuit, relay 406 locking itself in its energized position to springs 457 and its lower winding to ground through springs 471, and

at springs 458 opening the initial energizing circuit to permit-the impulsing relay 407 to restoreto start the rotary pulsing.

Rotary impaled n9 .Finder group 2 is now impulsed over circuits from ground through spring 471 and its make contact, normally closed springs controlled by armature 468, springs 464,

spring 459 and. its make contact, through wiper 421 of the finder allotter F A2 and thence through the winding of the rotary magnet to battery. Rotary magnet energizes, places ground uponurevertive pulse conductor 47 6 toenergize the impulsing relay 407 which at springs 464 interrupts the magnet circuit and at springs 463 prepares a testlng circuit, when the wipers of the finder are resting upon the contacts of the calling lino, battery potential placed on the private contacts to the upper winding of the cut. 06? relay picks up a private Wiper to complete a circuit to conductor leading to wiper of the finder allotter FA2, thence through v the lower winding of switch tlu'ough relay 408, the lower winding of impulse relay 407, springs 463 through the normally closed springs controlled by armature 468 through springs 471 and its make contact to ground,energizing the cut 011' relay, the switch through relay 408 and the impulse relay 407 in the manner similar to that which has been hereinbefore explained. Energization of switch through relay 408 of the control equipment C132, closes circuits to return that control equipment to normal, those circuits being duplicates to the one explained in connection with the control equipment CEI and will not be repeated at this time. 7

All finders busy condition.

As has been explained hereinbetore, as long as there is an idle finder in group 1. busy common conductor is maintained grounded, to maintain a short circuit upon the upper winding of groups busy relay 306 to prevent that relay energizing. Similarly as long as there is an idle finder in group 2, busy commonconductor 477 is grounded, to maintain a short circuit upon the upper winding of group busy relay 404 to prevent its energization. In the event one or the other of these group busy commons becomes ungrounded due to the taking for use of the last idle finder of the group, the corresponding group busy relay is energized, and-the start-circuits are altered so that a call originated in the group whose finders are all busy will be handled by the other group of finders, provided there are no calls in'progress in that group at the time. Assume now that the group 1 findersbecome'busy, conductor 77 will lose its ground and when the auxiliary start relay 301 deenergizes a circuit will be completed from ground on springs 327 and its break contact, through r- 349 andits make contact to conductor 375.

thence through break contacts 437 and 428, through the winding of relay 401 to battery. If a call is originated in group 1 while no call-s are in progress in group 2, the ground on the start conductor will energize relay 401 to prepare the group 2 control equipment CE2 for handling thecall. Relay 401, through springs 427 closes the circuit of the auxiliary start relay 409, which energizes and locks the two' relays in energized positions from ground on spring 407, as before. The energization of relay 401, at springs 430, 431 and 432 prepares the impulsing and change over circuits so that the relays 201 to 205 inclusive control the sending of vertical impulses to the finderthrough the second half of the-banks of counting switch CS2. then closed, being traceable from grounded spring 471 ,throughthe normally'closed con-- tactscontrolled by armature 468, conductor 473, springs 432, conductor 382, through wipers-225 and-the multiple contacts connected thereto, conductor 37 8, springs 430, and thence over the previously traced path through conductor 474 to the vertical magnet of the finder. Vhile the first'five impulses are being sentv no testing occurs, the vertical magnet circuit is as above traced. Vhen the counting switch S2 has taken its sixth step, bringing'wiper 225 into engagement with the contact to which conductor 260 is connected, testing takes place through the springs of the level relays 201-205, as before. Assume that the call is in the seventh level and relay 202 is energized, the

sixth pulse will go through as before, and

after the seventh pulse the switch over cir- The circuit of the vertical magnet is is completed when the'auxiliary start relay 409 restores, from ground through the break contact of spring 471, the upper winding of the relay 404, through resistance 472 to battery; Energizing that relay. which at springs 452 closes a circuit. through the upper winding of relay 403, to battery to energize that'relayto transfer'thegroup 2 conductor 371 to the control equipment CEl which is now assumed to be in readiness to handlea call. If a calling line in group 2] originates a call at this time, one of the'level relays, 207 for example, energizes and grounds'the start conductor 371 which now traverses a circuit through spring 436 and its make contact. over conductor 370, thr0ugh spring 350, springs 352, through the wind- I ing of start relay 309 to negative battery, to

register the call in the group 1' control equipment GEL Impulsing goes-on as be fore, through the medium'of the auxiliary start relay which is energized through springs 3560f the start relay 309. The

counting switch CS1 is'operate'd, under the control of relay 207 ,which is connected to the latter half of the banks swept over by the wipers of VSl and the line appears in the seventh level of the group l finders;

springs 367, thence through the previously traced circuit through conductor 394 tothe vertical magnet of the finder F. The first seven impulses are delivered over this circuit without change, atwhichtime wiper 220'is' 10a conductor 269 is connected, completing a in engagement with bank contact to which circuit through that conductor, springs 241, conductor 379, springs 361, conductor 395, springs 338 and thence through theupper winding of the switch over relay 304 to bat tery. Relay 304 energizes totransfer the impulsing circuit to the rotary magnet of the finder, as has been hereinbefore explained.

Thus it will medium of the two start relays 308 and 309, lines in either group can startthe control be seen that through the equipment (1E1 to control the finders of the 1 first group to pick up a'call, the relay 308 startinga group 1 call in-the controlequipment 1 and the relay 309 starting .agroup 2 call therein. 402 start control equipment. 2, 401 serving group 1 and 402 serving group 2. Control equipment CEl is provided with a key comprising springs 344 through which the switchroom attendant may throw that control equipmentv out of" service for repairs and ad ustment', that key serving to energize relay 306 through itslower windingzr The Similarly relays 401 and j I relay 306. on energizing, closes the circuit for relay 307 as before to switch the start w'ire 277 over to the other control equipment. Similarly, control equipment CE2 is provided with a key comprising springs 454 which when operated energize relay 404 to close a circuit for relay 403 and connect start 371 to. control equipment GEL Abandoned calls.

' From the foregoing description it will be before, 1 start testing in the level for the marked contact, which is non existent at this time, and therefore the finder will take eleven rotary steps, the eleventh step closing the cam springs 38, which upon closing complate a circuit from ground through those springs on conductor 74 to the upper winding of switch through relay 302, energizing that relayto switch through the control equipment and finder, the finder releases iminediately because the line relay 7 restores v and opens circuit of the release relay 8 permitting that relay to restore and remove ground from the release trunkv conductor. The control equipment .CEl releases to normal in'the usual manner, and the finder allotter FAl preselects another finder in readiness for the next call.

Revertz'oe pulse fails.

If for some reason or other the vertical or rotary magnets of the finder F fail to return ground over the revertive conductor 77, impulse relay 303 will not be energized, and after a brief interval slow-to-pull up relay 305 will energize, and at springs 343 close a circuit for the impulse relay 303 which energizes to terminate the impulse. If the failure to return the revertive pulse iS due to a dirty contact, the finder switch may be successfully operated at a slower rate of speed by the auxiliary repulse relay 305, in which case the impulses to the vertical and-rotary magnetsare long enough to insure their full'operation. If, however, the magnet is faulty and cannot completely energize, five impulses are sent to it, and the counting switch VSl encounters the sixth contact and the finder is switched over and rotated on its normal level to the eleventh rotary position, whereupon cam springs 38 operate and switch through the finder hereinbefore explained. Thus it will'be seen that the lVhile I have chosen to show my invention in connection with a particular type of system, employing a particular type of apparatus, I have done so by way of example only, as there are many adaptations and modifications which can be made by one skilled in the art, without departing from the scope of the invention, I am not to be limited by the specific disclosure made.

Having thus described my invention what I consider new and desireyto have protected by Letters Patent is pointed out in the appended claims. 7

WVhat is claimed is: i

1. In a telephone system, a group of lines, a plurality of groups of finder switches having access thereto, said lines being divided into subgroups each of which is first choicev to one of said groups of finders, and means:

responsive to the initiation of a call on any line for starting and directively controlling a finder switch in the group to which the subgroup containing said line is first choice.

2. In. a telephone system, a subscribers line, two finder switches having access to said line, and means responsive to a call on said line to startone or the other of said finders, one of the finders when operated being controlled by one digit to find said line, and the other finder when operated being controlled by another digit to find said line.

3. In a telephone system, a subscribers line, two finder switches having access to said line, a control equipment for each finder, means responsive to the initiation of a call on said line to register separate numbers representing said line in said control equipments, and'means controlled by said first means under normal condition for starting the finder in whose control equipment the lower number is registered to find lie the line, said last means under certain other conditions starting said other finder to find the line. v

4. In a. telephone system, a line, a pair of finder switches having, access thereto, said line being an early choice to one finder and a later choice for the other finder, means responsive to the initiation of a call for norinally directively controlling the early choice finder to find said line and for starting the later choice finder under certain other con ditions to find the line.

5. In a telephone system, a line, a group of finder switches having access thereto, means responsive to the initiation of a call from said line to register two difierent digits, and means responsive to conditions in the first of said finder groups and in the second half of the banks of the second of said finder groups, other of said lines appearing in the first half of the banks o1 said second finder group and in the second half. of the bank of the first finder group, and means responsive to the initiation of a call on any of said lines for preparing a control circuit to each of the said finder groups and for starting a finder switch in the group in which said calling line appears in the first half ofthe bank to establish a connection with said line.

7. In a telephone system, a group of lines, two groups of finder switches having access to said group of lines, certain of said lines appearing in the first half of the banks of second finder group and in the second half of the bank of the first finder group, and means responsive to the initiation of a call on one of said lines for preparing a control circuit to each of the said finder groups and for starting a finder in the group in which said line appears, in the second half of the banks, if all of said finders of the other group are busy.

8. In a telephone system, two groups 01": subscribers lines each divided into a plurality of subgroups, a finder switch mechanism having access to said group of lines, means responsive to the initiation of a call on one of said lines to start that finder switch, means for directively moving said finder switch to the subgroup containing the calling line, and means in said finder switch for simultaneously testing for said calling line in the subgroup containing it and in the corresponding subgroup of the other of said groups of lines.

9. In a telephone system, two groups of subscribers lines each divided into a plurality oi subgroups, a finder switch mechanism having access to said group of lines, means responsive tothe initiation of a call on one of said lines to start that finder switch, means for directively moving said finder switch tothe subgroup containing the calling line, and means including a test relay and circuit therefor for simultaneously testing in the selected subgroup and in the corresponding subgroup of the other line group in search of said calling line.

10. In a" telephone system, a two coordinate finder switch,two groups otsub scribers? lines, each divided into subgroups in accordance with the primary" movement of said finder switch, a control mechanism responsive to the initiation of a call on one of said lines: to move said finder in a primary direction to the subgroup containing said calling line, means also responsive to the initiation of said call for marking the contact of said subgroup associated with said line in a distinctive manner, wipers on said finder switch, means for then moving said switch in a secondary motion to bring certain of said wipers into engagement with contacts of the group containing the contacts marked by said calling line, and means in said finder switchfor simultaneously testing the contacts of-the group containingthe calling line and of the corresponding sub-- group of the other line group in searchoit said marked contact, and means responsive to the establishment of a circuit through said finder and said marked contact for stopping said finder and for returning said common equipment to its normal position.

ll. In combination with a group of finder switches which are directivelycontrolled, a line accessible to said finders, said line being an early choice to certain of said finders and a later choice to others of said finders, and means responsive to the initiation of a call for normally starting one of the early choice finders to find said line and for starting one of the later choice finders under certain other conditions to find the line.

12. In a telephone system, a group of lines, a group of finder switches having access to said lines, control equipment for said finders, means responsive to the initiation of a call on one of said lines for registering two numbers indicative of said line in said control equipment, and means in said control equipment responsive to said registration for directing one of said finders to said line under the control of one or the other of said registered numbers. a 13. The combination of a group of two directional finder switches which are directively operated during their primary move ment by a means external to the finders and which select a particular contact by their secondary movement under the control of devices in the finders themselves, and a group of lines each line of which is an early choice tocerta'in of said finders and. a later choice to others, and means responsive to the initiation of a call on one of said lines for preparing control circuits to both the early and latechoice finders and for starting the early choice find-er if it be'idle.

14. In a telephone system, a. group of lines divided into sub groups, two finder switches having access to said lines, said sub-v first of said finders and as a later choice to the other of said finders, a register relay for each of said subgroups, a control equipment for each of said finders, means responsive to the initiation of a, call on one of said lines for energizing the register relay of the subgroup containing that .line, means controlled by said register relay for registering a different digit in said control equipments, means also controlled by said register relay for starting the early choice finder if it is available or the later choice finder if the former is not available and for transmitting the digit registered in the control equipment of the selected finder to that finder, and means in said finder responsive to said digit for Selecting said subgroup and for searching for said calling line therein.

15. In a telephone system, a finder switch, an operating magnet in said finder,"means for closing a circuit to said operating magnet to energize it, a pulse ending relay, means controlled by said operating magnet in its energized position for energizing said pulse ending relay to open the circuit of said operating magnet, two test relays in said finder, means also controlled by said pulse end relay for extending a circuit through said test relays in multiple andsaid pulse ending relay in series therewith, and means for energizing one or the-other of said test relays over said circuit, said means locking said pulse ending relay energized to stop said finder.

16. In a telephone system, a finder switch containing an operating magnet. two test relays, and two test wipers a control equipment'including means for closing a circuit to said operating magnet to energize it, a pulse ending relay in said control equipment, means controlled by said operating magnetin its energized position for energizing said.

pulse ending relay to open the circuit of said operating magnet, a switch through relay in said control equipment, means also controlled by said pulse ending for extending a circuit through said pulse ending and switch through relays in series thence through parallel paths each including a test relay and a test wiper in series, means for energizing one or the otheriot' said test relays over said circuit, said means also locking said pulse ending relay energized to stop said finder and energizing said switch through relay, and

means controlled by said switch through relay for disengaging said control equipment from said linde c 17. In a telephone system, a finder switch containing an operating magnet, two test relays and two test wipers, two groups of subscribers lines, a test contact for each line 210-. cessible to the test wiper associated with that group, a control equipment associated with said finder, means in said control equipment responsive to the initiation of a call for closing a circuit to said operating magnet to energize it, means controlled by said operat ing magnet for energizing said pulse ending relay to open the circuit of said operating magnet, a switch through relay in said control equipment, means also controlled by said pulse ending relay for extending a circuit through said pulse ending relay, said switch through relay, thence through parallel paths each including a test relay and its associated test wiper and the test contact engaged there by, and means associated with the test contact of the calling line for energizing the test relay, whose wiper engages that contact over said circuit to establish a connection between the finder and the line, and for maintaining said pulse ending relay energized to stop the finder and for energizing said switch through relay to disassociate said control equipment from said. finder.

In witness whereof, I hereunto subscribe my name this third day of May, A. D. 1927.

RUDOLPH F. STEHL-IK. 

